1. Field of the Invention
The present invention relates generally to lead-tin eutectic solder. More particularly, the present invention relates to improving the fatigue resistance of lead-tin eutectic solder.
2. Description of Related Art
Eutectic and near-eutectic lead-tin solder alloys are used to provide solder joints in a wide variety of electronic devices. In addition to providing electrical connections, the solder joint provides a vital mechanical link between electronic devices and connectors.
During operation, many electrical devices are subjected to vibration and continual changes in temperature. Many times, the coefficient of thermal expansion of the various materials at and around the solder joint are different. As a result, the continual changes in temperature cause the solder joint to be continually subjected to varying degrees of stress and strain. The solder joint may also undergo continual stress due to vibrations and other forces exerted against the joint.
It would be desirable to provide solder joints which are structurally strong and resist fatigue due to mechanical or thermal stress and strain. Such fatigue resistant solder would be especially well-suited for use in electronic equipment which is subjected to extreme thermal fluctuations and mechanical duress. Further, fatigue resistant solder would be desirable for use in electronic devices where a long service life is required.